Phase change memory structures and methods

ABSTRACT

Methods, devices, and systems associated with phase change memory structures are described herein. One method of forming a phase change memory structure includes forming an insulator material on a first conductive element and on a dielectric material of a phase change memory cell, forming a heater self-aligned with the first conductive element, forming a phase change material on the heater and at least a portion of the insulator material formed on the dielectric material, and forming a second conductive element of the phase change memory cell on the phase change material.

TECHNICAL FIELD

The present disclosure relates generally to semiconductor memory devicesand methods, and more particularly, to phase change memory structuresand methods.

BACKGROUND

Memory devices are typically provided as internal, semiconductor,integrated circuits in computers or other electronic devices. There aremany different types of memory including random-access memory (RAM),read only memory (ROM), dynamic random access memory (DRAM), synchronousdynamic random access memory (SDRAM), phase change random access memory(PCRAM), and flash memory, among other types of memory.

Resistance variable memory devices, such as PCRAM devices, can include astructural phase change material such as a chalcogenide alloy, forinstance, which can be programmed into different resistivity states tostore data. The phase change memory cells are nonvolatile and theparticular data stored in a phase change memory cell can be read bysensing the cell's resistance (e.g., by sensing current and/or voltagevariations based on the resistance of the phase change material).

In cases in which the resistance variable memory device includes achalcogenide alloy, the chalcogenide alloy can exhibit a reversiblestructural phase change (e.g., from amorphous to crystalline). A smallvolume of the chalcogenide alloy can be integrated into a circuit thatcan allow the cell to act as a fast switching programmable resistor.This programmable resistor can exhibit greater than 40 times the dynamicrange of resistivity between the crystalline state (low resistivity) andthe amorphous state (high resistivity), and is also capable ofexhibiting multiple intermediate states that allow multi-bit storage ineach cell. That is, resistance variable memories may achieve multi-levelcell (MLC) functionality via programming of memory cells to one of anumber of different resistance levels.

The reliability of phase change memory cells over time can be affectedby various factors such as the adhesion between the phase changematerial and underlying substrate and/or the current densities used toprovide sufficient power to melt the phase change material, among otherfactors. As an example, large current density can cause undesiredelectro-migration in conductive materials of a phase change memory celland may cause phase separation in the phase change material, in someinstances.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a portion of a phase change memory array havingone or more phase change memory structures in accordance with one ormore embodiments of the present disclosure.

FIGS. 2A-2D are cross-sectional views illustrating formation of a phasechange memory structure in accordance with one or more embodiments ofthe present disclosure.

FIG. 3 illustrates a cross-sectional view of a portion of a phase changememory structure in accordance with one or more embodiments of thepresent disclosure.

FIG. 4 is a cross-sectional view of a portion of a memory device inaccordance with one or more embodiments of the present disclosure.

DETAILED DESCRIPTION

Methods, devices, and systems associated with phase change memorystructures have been described. One method of forming a phase changememory structure includes forming an insulator material on a firstconductive element and on a dielectric material of a phase change memorycell, forming a heater self-aligned with the first conductive element,forming a phase change material on the heater and at least a portion ofthe insulator material formed on the dielectric material, and forming asecond conductive element of the phase change memory cell on the phasechange material.

Embodiments of the present disclosure can provide various benefits suchas providing improved adhesion between a phase change material and theunderlying substrate and reducing the programming current densityassociated with phase change memory cells, as compared to previous phasechange memory cells. Reducing the programming current density canincrease the reliability of phase change memory cells, among otherbenefits.

In the following detailed description of the present disclosure,reference is made to the accompanying drawings that form a part hereof,and in which is shown by way of illustration how one or more embodimentsof the disclosure may be practiced. These embodiments are described insufficient detail to enable those of ordinary skill in the art topractice the embodiments of this disclosure, and it is to be understoodthat other embodiments may be utilized and that process, electrical,and/or structural changes may be made without departing from the scopeof the present disclosure. As used herein, the designators “N” and “M,”particularly with respect to reference numerals in the drawings,indicate that a number of the particular feature so designated can beincluded with one or more embodiments of the present disclosure.

The figures herein follow a numbering convention in which the firstdigit or digits correspond to the drawing figure number and theremaining digits identify an element or component in the drawing.Similar elements or components between different figures may beidentified by the use of similar digits. For example, 101 may referenceelement “01” in FIG. 1, and a similar element may be referenced as 401in FIG. 4. As will be appreciated, elements shown in the variousembodiments herein can be added, exchanged, and/or eliminated so as toprovide a number of additional embodiments of the present disclosure. Inaddition, the proportion and the relative scale of the elements providedin the figures are intended to illustrate various embodiments of thepresent invention and are not to be used in a limiting sense.

As used in this disclosure, the terms “wafer” and “substrate” are usedinterchangeably and are to be understood as includingsilicon-on-insulator (SOI) or silicon-on-sapphire (SOS) technology,doped and undoped semiconductors, epitaxial layers of silicon supportedby a base semiconductor foundation, and other semiconductor structures.Furthermore, when reference is made to a “wafer” or “substrate” in thefollowing description, previous process steps may have been utilized toform regions or, junctions in the base semiconductor structure orfoundation.

FIG. 1 is a schematic of a portion of a phase change memory array 100having one or more phase change memory structures in accordance with oneor more embodiments of the present disclosure. In the embodimentillustrated in FIG. 1, the memory array 100 includes a number of phasechange memory cells each having an associated access device 101 andresistance variable element 103 (e.g., a phase change material 103). Theaccess devices 101 can be operated (e.g., turned on/off) to access thememory cells in order to perform operations such as data programming(e.g., writing) and/or data sensing (e.g., reading) operations on theresistance variable elements 103.

In the embodiment illustrated in FIG. 1, the access devices 101 aremetal oxide semiconductor field effect transistors (MOSFETs). As shownin FIG. 1, a gate of each MOSFET 101 associated with each memory cell iscoupled to one of a number of access lines 105-0 (WL0), 105-1 (WL1), . .. , 105-N (WLN) (i.e., each access line 105-0, 105-1, . . . , 105-N iscoupled to a row of phase change memory cells). The access lines 105-0,105-1, . . . , 105-N may be referred to herein as “word lines.” Thedesignator “N” is used to indicate that a memory array can include anumber of word lines.

The resistance variable elements 103 can be a phase change chalcogenidealloy such as a Germanium-Antimony-Tellurium (GST) material (e.g., aGe—Sb—Te material such as Ge₂Sb₂Te₅, Ge₂Sb₂Te₇, Ge₁Sb₂Te₄, Ge₁Sb₄Te₇,etc. The hyphenated chemical composition notation, as used herein,indicates the elements included in a particular mixture or compound, andis intended to represent all stoichiometries involving the indicatedelements. Other phase change materials can include Ge—Te, Sb—Te, Ge—Sb,Ga—Sb, In—Sb, As—Te, Al—Te, Ge—Sb—Te, Te—Ge—As, In—Sb—Te, Te—Sn—Se,Ge—Se—Ga, Bi—Se—Sb, Ga—Se—Te, Sn—Sb—Te, In—Sb—Ge, Te—Ge—Sb—S,Te—Ge—Sn—O, Te—Ge—Sn—Au, Pd—Te—Ge—Sn, In—Se—Ti—Co, Ge—Sb—Te—Pd,Ge—Sb—Te—Co, Sb—Te—Bi—Se, Ag—In—Sb—Te, Ge—Sb—Se—Te, Ge—Sn—Sb—Te,Ge—Te—Sn—Ni, Ge—Te—Sn—Pd, and Ge—Te—Sn—Pt, among various other phasechange materials.

In the embodiment illustrated in FIG. 1, each resistance variableelement 103 is coupled to one of a number of data lines 107-0 (BL0),107-1 (BL1), . . . , 107-M (BLM) (i.e., each data line 107-0, 107-1, . .. , 107-M is coupled to a column of phase change memory cells). The datalines 107-0, 107-1, . . . , 107-M may be referred to herein as “bitlines” or “sense lines.” The designator “M” is used to indicate that amemory array can include a number of bit lines. For ease of addressingin the digital environment, the number of word lines 105-1, . . . ,105-N and the number of bit lines 107-1, . . . , 107-M can each be somepower of two(e.g., 256 word lines by 4,096 bit lines). However,embodiments are not limited to particular numbers of word lines and/orbit lines.

In operation, appropriate voltage and/or current signals (e.g., pulses)can be applied to the bit lines 107-0, 107-1, . . . , 107-M and wordlines 105-0, 105-1, . . . , 105-N in order to program data to and/orread data from the phase change memory cells of the array 100. As anexample, the data stored by a phase change memory cell of array 100 canbe determined by turning on an access device 101 and sensing a currentpassing through the phase change element 103. The current sensed on thebit line associated with the memory cell being read corresponds to aresistance level of the phase change element 103, which in turncorresponds to a particular data value (e.g., a binary value such as 1,0, 001, 111, 1011, etc.)

Embodiments of the present disclosure are not limited to the examplearray 100 illustrated in FIG. 1. For example, the access device 101associated with a particular memory cell can be a device other than aMOSFET. In some embodiments, the access device 101 can be a bipolarjunction transistor (BJT) or a diode (e.g., p-n diode, a Schottky diode,or a Zener diode), among other types of access devices. Although notillustrated in FIG. 1, one of ordinary skill in the art will appreciatethat the phase change memory array 100 can be coupled to other memorycomponents including a controller and various write/read circuitryand/or other control circuitry.

FIGS. 2A-2D are cross-sectional views illustrating formation of a phasechange memory structure in accordance with one or more embodiments ofthe present disclosure. The memory cell structure shown in FIGS. 2A-2Dincludes a base semiconductor structure that includes a substrate 202including a conductive contact 206 formed in a dielectric material 204.The substrate 202 can be a silicon substrate, silicon on insulator (SOI)substrate, or silicon on sapphire (SOS) substrate, among others. Thedielectric material 204 can be a nitride or oxide such as silicondioxide (SiO₂) or silicon nitride (SiN), among other dielectricmaterials. The conductive contact 206 can be made of a metal (as shownin FIGS. 2A-2D) such as tungsten (W) or other suitable conductivematerial and can be formed in the dielectric material 204 via a maskingand etching process, for instance. Although not shown in FIGS. 2A-2D,the contact 206 can be coupled to an access device (e.g., an accesstransistor) corresponding to a particular memory cell (e.g., a PCRAMcell such as shown in FIG. 1).

The structure shown in FIGS. 2A-2D includes a first conductive element208 (e.g., a first electrode) formed on the conductive contact 206. Thefirst conductive element 208 can be a bottom electrode (BE) 208. Thebottom electrode 208 can be a conductive material such as titanium (Ti),titanium nitride (TiN) (e.g., titanium rich TiN), tantalum (Ta), and/ortantalum nitride (TaN), for example. The bottom electrode 208 can beformed by masking and etching, among other suitable processes. One ormore side surfaces of the bottom electrode 208 are in contact with thedielectric material 204.

As illustrated in FIG. 2A, forming a phase change memory structure inaccordance with one or more embodiments of the present disclosureincludes forming an insulator material 212 on the bottom electrode 208and the dielectric material 204. In one or more embodiments, an uppersurface of the dielectric material 204 and/or the bottom electrode 208can be planarized via chemical mechanical planarization (CMP) or othersuitable processes prior to forming the insulator material 212 thereon.

The insulator material 212 can be a material such as aluminum nitride(AlN) or silicon nitride (SiN), for example, and can provide an adhesiveinterface between the dielectric material 204 and a phase changematerial, such as phase change material 216 described in connection withFIGS. 2C-2D. That is, the adhesion between the insulator material 212and a phase change material formed thereon is greater than the adhesionbetween the dielectric material 204 and the phase change material formedthereon, in various embodiments. As such, the insulator 212 can bereferred to as an insulative adhesion material. Improved adhesionbetween a phase change material and the underlying substrate can providebenefits such as increasing the long term reliability of a phase changememory device, among other benefits.

The insulator material 212 can have a thickness of between about 2 nm-3nm; however, embodiments are not limited to a particular thickness. Forinstance, in some embodiments, the thickness of the insulator material212 is not more than about 10 nm. However, the thickness of theinsulator 212 can be less than about 2 nm or greater than about 10 nm,in various embodiments.

FIG. 2B illustrates an interfacial heater 214. In various embodiments,the heater 214 is self-aligned with the bottom electrode 208. The heater214 can be formed, for example, by modifying a portion of the insulatormaterial 212 (e.g., a portion of material 212 formed on the bottomelectrode 208). In one or more embodiments, modifying the insulatormaterial 212 to form the self-aligned heater 214 includes creating areaction between the insulator material 212 and the bottom electrodematerial 208 such that the heater 214 is a different material than theinsulator 212. As an example, the reaction can be created by heating thebottom electrode 208 and/or the insulator material 212 formed thereon.

For instance, the memory structure illustrated in FIG. 2A can be heatedvia a thermal anneal process such as a rapid thermal annealing (RTA),laser annealing, or a microwave heating process, among other heatingprocesses. Such a process can promote a solid-state reaction between theinsulator material 212 and the bottom electrode 208.

As one example, the bottom electrode 208 can be a titanium nitride (TiN)material and the insulator material 212 can be an aluminum nitride (AlN)material. In such an embodiment, a thermal anneal process (e.g., in N₂at about 500° C. for about 5 minutes) can form epitaxial titaniumaluminum nitride (e.g., Ti₂AlN) as the heater 214. In some embodiments,thermal reaction of a TiN bottom electrode 208 with an AlN insulator 212can form heaters 214 having other TiAlN alloy phases such as Ti₃Al₂N₂and Ti₃AlN, for instance.

As another example, the bottom electrode 208 can be a titanium (Ti)electrode and the insulator material 212 can be AlN. Since the Ti bottomelectrode 208 may oxidize (e.g., after a CMP process performed on thesurface of the bottom electrode 208), further processing may be used toreduce the titanium oxide (TiOx) to Ti prior to the heating process usedto modify the insulator material 212. For instance, an in situ plasmatreatment can be used to reduce at least a portion of the TiOx totitanium metal. As an example, the TiOx can be exposed to a non-thermalplasma such as an electrical discharge plasma, a microwave-drivennon-thermal plasma, a dielectric barrier plasma, a pulsed coronadischarge plasma, a glow discharge plasma, and/or an atmosphericpressure plasma jet, among other non-thermal plasmas. The reduced Ti canthen react with the AlN of the insulator material 212 to form Ti₂AlN orother titanium aluminum nitride alloy phase.

As another example, the bottom electrode 208 can be a tantalum nitride(TaN) electrode and the insulator material 212 can be SiN. In such anembodiment, a thermal anneal process performed on the structure can forma tantalum silicon nitride (TaSiN) heater 214.

As illustrated in FIG. 2C, a phase change material 216 can be formed onthe insulator material 212 and the bottom electrode 208, and a secondconductive element 218 (e.g., a top electrode) can be formed on thephase change material 216. The top electrode 218 can be a bit line of aphase change memory cell or can be coupled to a bit line of the cell(e.g., via a contact plug).

FIG. 2D illustrates an active region 220 of the phase change material216. The active region 220 represents the portion of the phase changematerial 216 that changes phase (e.g., from crystalline to amorphous andvice versa) in response to heating due to current flow between thebottom electrode 208 and top electrode 218.

The self-aligned heater 214 at the interface between the bottomelectrode 208 and the phase change material 216 provides variousbenefits. For instance, the heater 214 provides localized heat to thephase change material 216, which can assist with switching of the activeregion 220 and/or can reduce the current density required to induceswitching as well as the power associated with operating the memorycell. The heater 214 has a low thermal conductivity compared to thebottom electrode 208, which reduces heat loss to the bottom electrode208 (e.g., due to the heat sink effect). The heater 214 also has a highresistivity compared to the bottom electrode 208, such that the heater214 can conduct current with a high temperature tolerance, which canincrease the phase change memory cell integrity and/or reliability, forinstance.

In some embodiments, the heater 214 can be formed via a masking andetching process. For example, a portion of the insulator material 212(e.g., the portion formed on the bottom electrode 214) can be removed(e.g., via an etching process), and a material 214 (e.g., Ti₂AlN) can bedeposited in its place. However, masking and etching to form thematerial 214 on the bottom electrode can include additional processingsteps as compared to previous methods described above and do not provideself-alignment of the heater 214 with the bottom electrode 208.

As described below in connection with FIG. 4, the memory structureillustrated in FIG. 2D can be coupled to an access device (e.g., anaccess transistor) and other components and/or circuitry correspondingto a particular memory cell (e.g., a PCRAM cell such as shown in FIG.1).

FIG. 3 illustrates a cross-sectional view of a portion of a phase changememory structure in accordance with one or more embodiments of thepresent disclosure. The example shown in FIG. 3 is a confined phasechange memory cell structure including a base semiconductor structurethat includes a substrate 302 including a conductive contact 306 formedin a dielectric material 304. A dielectric material 313 is formed on thecontact 306 and dielectric material 304. A via can be formed in thedielectric material 313 and a bottom electrode 308 can be depositedtherein. A heater material 314 can be formed on the bottom electrode 308and a phase change material 316 can be formed on the heater 314. Theheater 314 can be formed by modifying an insulator material formed onthe bottom electrode, as described above in connection with FIGS. 2A-2D.For instance, the heater 314 can be formed via a heating process such asa thermal anneal process, laser annealing process, or microwave heatingprocess, for example. The phase change memory structure shown in FIG. 3includes a top electrode 318 formed on the phase change material 316 andthe dielectric material 313.

FIG. 4 is a cross-sectional view of a portion of a memory device 450 inaccordance with one or more embodiments of the present disclosure. Thememory device 450 includes a number of phase change memory cellstructures formed in accordance with embodiments described herein. Theexample illustrated in FIG. 4 includes a first stack 430-1 and a secondstack 430-2. The first stack 430-1 corresponds to a first phase changememory cell, and the second stack 430-2 corresponds to a second phasechange memory cell (e.g., phase change memory cells such as thosedescribed in FIG. 1). The separate stacks 430-1 and 430-2 can be formedby a masking and etching process through the appropriate materials, forexample.

Each of the stacks 430-1 and 430-2 includes a respective top electrode(TE) 418-1 and 418-2 formed on a respective phase change material (e.g.,GST) 416-1 and 416-2. The phase change material 416-1 and 416-2 isformed on an insulator 412-1 and 412-2 as well as an interfacial heater414-1 and 414-2 self-aligned with a respective bottom electrode 408-1and 408-2.

The heaters 414-1 and 414-2 can be formed by modifying a portion of theinsulator material 412-1 and 412-2, as described above in connectionwith FIGS. 2A-2D. For example, a heating process can be used to create areaction between the bottom electrode (BE) material 408-1/408-2 (e.g.,Ti as shown) and the insulator material 412-1/412-2 (e.g., AlN as shown)to form the interfacial heaters 414-1/414-2 (e.g., Ti₂AlN as shown). Theinsulator material 412-1 and 412-2 can provide an adhesive interfacebetween the phase change materials 416-1 and 416-2 and the underlyingdielectric material 404 (e.g., SiO₂)

The bottom electrodes 408-1 and 408-2 are formed in the dielectricmaterial 404, which is formed on respective conductive contacts 446. Inthis example, the contacts 446 are drain contacts. That is the contacts446 couple the stacks 430-1 and 430-2 to a drain region 444 of arespective access device 401 (e.g., an access transistor). In thisexample, the access devices 401 are MOSFET (metal oxide semiconductorfield effect transistor) devices having associated source 443, drain444, and gate 445 regions and are formed on a base substrate 402.However, embodiments are not limited to a particular type of accessdevice. For instance, as described above, the access devices 401 can bediodes or BJTs, among other types of access devices for operating phasechange memory cells. As an example, the substrate 402 can be a p-typesemiconductor substrate with n-type source 443 and drain 444 regions.

The phase change memory device 450 also includes a source contact 447coupled to the source region 443 of one or more of the access devices401. The source contact 447 and drain contacts 446 are formed in adielectric material 448 (e.g., SiO₂) and a dielectric material 449(e.g., SiN) is formed around the gate stacks of the transistors 401 toelectrically insulate the transistors 401 from the contacts 446 and 447.Embodiments are not limited to particular dielectric materials 448 and449.

As described above, phase change memory cell structures in accordancewith embodiments described herein can provide various benefits. Forinstance, the self-aligned heaters 414-1 and 414-2 can provide localizedheat to the active regions 420-1 and 420-2 of the memory cells, whichcan reduce the current required to induce structural phase transitionswithin the active regions. Reducing the current can reduce the powerconsumption associated with a memory device and can improve the longterm reliability and/or integrity of the memory device. The adhesiveinsulator material 412-1 and 412-2 can improve adhesion between thephase change material 416-1 and 416-2 and the underlying substrate, ascompared to previous approaches. Furthermore, modifying portions of theinsulator material 412-1/412-2 via a heating process to form theself-aligned heaters 414-1/414-2 can provide various benefits withoutincreasing the complexity of the fabrication processes.

CONCLUSION

Methods, devices, and systems associated with phase change memorystructures have been described. One method of forming a phase changememory structure includes forming an insulator material on a firstconductive element and on a dielectric material of a phase change memorycell, forming a heater self-aligned with the first conductive element,forming a phase change material on the heater and at least a portion ofthe insulator material formed on the dielectric material, and

forming a second conductive element of the phase change memory cell onthe phase change material.

Although specific embodiments have been illustrated and describedherein, those of ordinary skill in the art will appreciate that anarrangement calculated to achieve the same results can be substitutedfor the specific embodiments shown. This disclosure is intended to coveradaptations or variations of various embodiments of the presentdisclosure.

It is to be understood that the above description has been made in anillustrative fashion, and not a restrictive one. Combination of theabove embodiments, and other embodiments not specifically describedherein will be apparent to those of skill in the art upon reviewing theabove description. The scope of the various embodiments of the presentdisclosure includes other applications in which the above structures andmethods are used. Therefore, the scope of various embodiments of thepresent disclosure should be determined with reference to the appendedclaims, along with the full range of equivalents to which such claimsare entitled.

In the foregoing Detailed Description, various features are groupedtogether in a single embodiment for the purpose of streamlining thedisclosure. This method of disclosure is not to be interpreted asreflecting an intention that the disclosed embodiments of the presentdisclosure have to use more features than are expressly recited in eachclaim.

Rather, as the following claims reflect, inventive subject matter liesin less than all features of a single disclosed embodiment. Thus, thefollowing claims are hereby incorporated into the Detailed Description,with each claim standing on its own as a separate embodiment.

What is claimed is:
 1. A method of forming a phase change memorystructure, the method comprising: forming an insulator material on afirst conductive element and on a dielectric material of a phase changememory cell; forming a heater self-aligned with the first conductiveelement; forming a phase change material on the heater and at least aportion of the insulator material formed on the dielectric material; andforming a second conductive element of the phase change memory cell onthe phase change material.
 2. The method of claim 1, including formingthe heater by modifying a portion of the insulator material.
 3. Themethod of claim 2, including forming the phase change material on theheater and on an unmodified portion of the insulator material.
 4. Themethod of claim 2, wherein modifying the portion of the insulatormaterial includes heating the portion of the insulator material.
 5. Themethod of claim 4, wherein heating the portion of the insulator materialincludes at least one of: a rapid thermal annealing (RTA) process; alaser annealing process; and a microwave heating process.
 6. The methodof claim 2, wherein modifying the portion of the insulator materialincludes creating a reaction between the insulator material and amaterial of the first conductive element to form the heater.
 7. Themethod of claim 6, wherein the insulator material is aluminum nitride(AlN), the material of the first conductive element is at least one oftitanium (Ti) and titanium nitride (TiN), and wherein the reaction formsa titanium aluminum nitride (TiAlN) heater.
 8. The method of claim 6,wherein the insulator material is silicon nitride (SiN), the material ofthe first conductive element is at least one of titanium nitride (TiN)and tantalum nitride (TaN), and wherein the reaction forms at least oneof a titanium silicon nitride (TiSiN) heater and a tantalum siliconnitride (TaSiN) heater.
 9. The method of claim 1, including forming theheater self-aligned with the first conductive element via a masking andetching process.
 10. The method of claim 1, wherein forming the firstconductive element includes forming a bottom electrode and forming thesecond conductive element includes forming a top electrode.
 11. A methodof forming a phase change memory structure, the method comprising:forming an insulative adhesion material on a first electrode of a phasechange memory cell; forming an interfacial heater self-aligned with thefirst electrode by heating at least a portion of the insulative adhesionmaterial, the interfacial heater being a material different than theinsulative adhesion material; forming a phase change material on theinterfacial heater; and forming a second electrode on the phase changematerial.
 12. The method of claim 11, including: forming the firstelectrode such that a side surface of the first electrode is in contactwith a dielectric material; and forming the insulative adhesion materialon at least a portion of an upper surface of the dielectric material.13. The method of claim 12, including forming the phase change materialon an upper surface of the interfacial heater and on an upper surface ofat least a portion of the insulative adhesion material.
 14. The methodof claim 11, including: forming the first electrode by depositing anelectrode material in a via formed in a dielectric material; andperforming a planarization process on the first electrode prior toforming the insulative adhesion material on the first electrode.
 15. Themethod of claim 11, wherein heating the at least a portion of theinsulative adhesion material includes performing a thermal annealingprocess on the phase change memory structure.
 16. The method of claim11, wherein heating the at least a portion of the insulative adhesionmaterial includes performing a microwave heating process on the at leasta portion of the insulative adhesion material.
 17. The method of claim11, wherein heating the at least a portion of the insulative adhesionmaterial includes performing a laser annealing process on the at least aportion of the insulative adhesion material.
 18. The method of claim 11,including reducing oxidation of the first electrode by performing an insitu plasma treatment process prior to forming the insulative adhesionmaterial on the first electrode and prior to heating the at least aportion of the insulative adhesion material.
 19. A phase change memorystructure, comprising: a bottom electrode having a side surface incontact with a dielectric material; a phase change material between thebottom electrode and a top electrode; an insulator material having afirst portion providing an adhesive interface for at least a portion ofthe phase change material; and an interfacial heater self-aligned withthe bottom electrode and positioned between the bottom electrode and thephase change material; wherein the interfacial heater is a modifiedportion of the insulator material and is a material different from theinsulator material.
 20. The memory structure of claim 19, wherein thefirst of the insulator material is formed on a planarized surface of thedielectric material and the bottom electrode.
 21. The memory structureof claim 19, wherein the bottom electrode is formed in a via formed inthe dielectric material, and wherein the adhesive interface provided bythe first portion of the insulator material includes increased adhesionas compared to adhesion between the phase change material and thedielectric material.
 22. The memory structure of claim 19, wherein theself-aligned interfacial heater is formed by a reaction between theinsulator material and a material of the bottom electrode.
 23. Thememory structure of claim 19, wherein the insulator material has athickness of less than about 10 nm.
 24. The memory structure of claim19, wherein the bottom electrode is coupled to a metal contact, andwherein the metal contact is coupled to at least one of a source and adrain region of an access transistor corresponding to the phase changememory structure.
 25. The memory structure of claim 19, wherein theinsulator material is at least one of aluminum nitride (AlN) and siliconnitride (SiN).
 26. The memory structure of claim 25, wherein theinterfacial heater includes a material from the group including:titanium aluminum nitride (TiAlN) titanium silicon nitride (TiSiN); andtantalum silicon nitride (TaSiN).
 27. A phase change memory cell,comprising: an access device; a first electrode coupled to the accessdevice via a conductive contact; an interfacial heater formed on, andself-aligned with, the first electrode; a phase change material formedon the self-aligned interfacial heater and on at least a portion of aninsulator material formed on a dielectric material having a side surfacein contact with the first electrode; and a second electrode formed onthe phase change material; wherein the self-aligned interfacial heateris a portion of the insulator material modified via a heating processsuch that the self-aligned interfacial heater is a material differentfrom the insulator material.
 28. The device of claim 27, wherein theinterfacial heater is configured to generate heat to assist withprogramming of the memory cell.
 29. The device of claim 27, wherein theinterfacial heater has a thermal conductivity conducive to reducing heatloss to the first electrode.
 30. A method of operating a phase changememory cell, the method comprising: programming the memory cell byproviding a voltage difference between a top and bottom electrode of thephase change memory cell; and providing localized heating to an activeregion of a phase change material of the memory cell via an interfacialheater formed on, and self-aligned with, the bottom electrode; whereinthe interfacial heater generates heat responsive to the voltagedifference which assists with switching of a state of the active regionto program the memory cell.
 31. The method of claim 30, wherein theinterfacial heater is a modified portion of a dielectric materiallocated between the phase change material and the bottom electrode.